Digester



(No Model.) 2 Sheets-Sheet 1,

W.. T. FORBES. DIGESTER.

No. 439,033. Patented 001;. 21, 1390.

D000 6 U 0000 O0 0000 DO 0000 00 000 0O 00 9. 29999 0000 DO 0000 OO O0000 O0 0000 O0 0000 O0 000 ooOOQo 000000 000 OD 000000 00000 O 00000000 (No Model.) 2 Sheets-Sheet 2. W. T. FORBES. DIGBSTBR.

No.439,033. PatentedOct.21, 1890.

I m I a sa Q WITNESSES ATTORNEY.

we worms virus on. mcn'mumm. WASHINGTON. o. c.

UNITED STATES PATENT OFFICE.

l/VALTER T. FORBES, OF ATLANTA, GEORGIA.

DIGESTER.

SPECIFICATION forming part of Letters Patent No. 439,033, dated October21, 1890.

Application filed April 2. 1890. Serial No. 346,316. (No model.)

To all whom it may concern.-

Be it known that I, WALTER '1. FORBES, a citizen of the United States,and a resident of Atlanta, in the county of Fulton, State of Georgia,have invented certain new and useful Improvements in Digesters; and I dodeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawings, and to letters of reference marked there on,which form a part of this specification.

This invention relates to devices in which solid substances may betreated with liquids for the removal by solution or washing of certainof their elements, inherent or foreign, or their disintegration, whichsaid devices are commonly known as digesters, the present device beingmainly intended for the digesting of paper-pulp and for disintegratingfibrous plants for the production or laying bare of their fibrousstructure, the means for which and the details of construction wherebythese ends are attained being hereinafter fully set forth, and the partsheld to be new pointed out in the claims.

In the accompanying drawings, Figure 1 is a vertical longitudinalsection of the digester, showing one form of such device. Fig. 2 is avertical longitudinal section of another form of digester equivalent inits details to the one shown in Fig. 1, and Fig; 3 is a detail verticalsection of the false bottom, showing the arran gement of theperforations.

In the figures like reference-marks indicate corresponding parts in allthe views.

The digesterA has an outer shell a, having bottom plate a and cover awhich cover is removable by being bolted by swivel-bolts of, havingtail-nuts to the flange a, around the top edge of the casing a, over theaperture through which the material to be treated is charged into theinner chamber. Said digester A also has a perforated false shell asecured in place by the rings a, placed between the outer shell and theshell (1 in such a manner as to form partitions separating the annularchamber a, so formed from the interior chamber, while the rings a placedin substantially the position shown, further support the said shell aand form a division a of the annular chamber a. The annular chambers aare connected by pipes 17 with a supply-pipe B, which forms a conduitfrom a pump of suitable character to force into the inner chamberthrough the perforations in the shell a the liquid solvent, said pipesI) being cut by valves 1) for the purpose of regulating the inflow ofliquor, and hence the force of the circulation and the pressure on thematerial. The chamber a also annular in form,has connection bydischarge-pipe a with a suitable reservoirv for heating or storing theliquor, so that it may be used again or directly with thehereinbefore-mentioned force-pump and is cut by a valve a.

To prevent the material being treated from packing in the center of thedigester and to more thoroughly agitate it and mix it with the liquor, aperforated pipe 0, connecting with a supply-pipe O is provided, which,in the construction shown in Fig. l, enters at the bottom through theplate a, and its upper end, which is stopped against outflow of liqnor,is inserted in a depression 0 in the cover 0. In order to be easilyremovable the said column is screwed into a plate 0, bolted to the platea, and the plate 0 which is also bolted to said plate a, has screwedinto it the pipe 0 which interiorly connects through an opening in thesaid plate awith the column a and supplies liquor thereto, the flowbeing governed by the valve 0 cutting said pipe 0 In Fig. 2 the column 0is shown entering through a packed gland in the cover a while lateraland downward motion is effectually prevented by the step 0 supported byarms 0 extending to the walls of the interior chamber. At suitablepoints, screwed into the circumference of the casing near its lower end,are outlet-pipes d, out by suitable valves 01', which pipes are for thepurpose of drawing off the pulp after having been thoroughly' treated orthe process finished. In order that the discharge through these pipes dof the material may be free, however hard it may be packed by itsgravity, a false bottom D is placed within the inner chamber at thebottom of the shell a, which part D is secured to said casing and formsthe upper wall of the chamber 01 the bottom plate a being the otherwall. Said plate D is perforated, as shown, the general direction of theperforations being at right angles to the sides of the digester, ornearly so, and in the direction of the flow of material to the sides atthe bottom in the construction shown in Fig. 1, or to the center in thatshown in Fig. 2. The material will, by its own gravity, settle to thebottom, where it will be broken up and assisted to flow down and out bythe liquor which is forced into the chamber (1 formed by the plateD,-through the pipe d or equivalent conduit. In order to prevent theinternal pressure from forcing material from the inner chamber into thesaid chamber under plate D through the perforations during the digestingor disintegrating operation, the central column G is perforated betweensaid plates '1) and a, which insures a continual pressure on the chamberd" equal to that on the inner chamber.

Fig. 2 illustrates, together with the modifie details already described,the digester having its upper end conoidal in form for reducing the areasubjected to force from internal pressure, a pipe dentering the chamber(Z from the manifold B, a false bottom D of an inverted conoidal formcarrying the pulp to a central discharge-pipe d.

If desired or necessary for any purpose whatever, the perforations ofany part of the device may be restricted by the application of awire-guaze fabric 011 the necessary side of the perforated plate. Anexample of this is shown in Fig. 2, and said construction operates toprevent the pulp, however fine, from escaping from the inner ordigesting chamber.

The operation of this device is as follows: The cover a the nuts (0being released, is raised from its normal position, thus opening the topof the digester. The material to be digested is then charged into theinner chamber in the desired quantity and in the desired condition,after which the cover a is returned to its position, the upper end ofthe pipe C entering the depression 0, after which the swivel-bolts areturned up and the nuts tightened, holding the cover securely in place.The valves 0 and Z), governing, respectively, inlet communication withthe pipe 0 and the annular chamber a and the valve a, governing outletcommunication between the chambers a and the spent-liquor receiver, areopened. The pump handling the liquor is then started, forcing saidliquor through the supply-pipe B and the pipes 12 into the chambers 6L9,thence through the perforated shell a into the material to be digested.From thence it will go through the chamber a and the pipe a back to thepump or to a suitable receiver or heating-coil. The circulation of theliquor will be thus continued at the desired temperature, internalpressure, and speed until the material shall be sufficiently digested,or, in the case of fibrous vegetable growths, disintegrated, after whichthe valves d in the outlet-pipes d would be opened, the circulationcontinued or not, as desired, the valves 0 opened, causing a circulationof liquor through the openings in the plate D in a directionsubstantially the same as the outflowing material, which outflow willcontinue till the digestcr will be emptied of its solid contents, whenall the valves will be closed and the operation, as above described,repeated.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. In a digester, the combination of an outer and an inner shell, thelatter being perforated, the partitions ct and a between the shellsforming the annular chambers ar and a", a supply-pipe connecting wit-hthe chambers (t and a discharge-pipe connecting with chamber asubstantially as and for the purpose specified.

2. In a digester, the combination of the perforated shell forming thedigesting-chamber, the outer shell surrounding said perforated shell, afalse conoidal-shaped bottom D, forming a chamber a in the lower part ofthe digesting-chamber, said false bottom being perforated at rightangles to the sides of the digester, the supply-pipe entering saidchamber ct, and the outlet-pipe cl, connecting with the lower part ofthe main chamber, substantially as and for the purpose specified.

3. In a digester, the combination of the outer shell, the perforatedinner shell, the false perforated conoidal-shaped bottom forming achamber in the lower part of the inner shell, the partitions a and aforming annular chambers a and a between the shells, the supply-pipeconnecting with the upper and lowest of said chambers, the perforatedpipe connecting with the supply-pipe and passing upward through thedigester, the discharge pipe connecting with the intermediate chamber,and the outlet-pipe connecting with the lower part of thedigesting-chamber, substantially as and for the purpose specified.

In testimony whereof I hereunto atfix my signature in presence of twowitnesses.

WALTER T. FORBES.

Witnesses:

A. P. W001), S. M. W001).

